Lots of tone testing today on my 100w Helios. With volume maybe loud enough for a soft drummer, my guitar with EMG’s sounds like the bottom end is fuzzy like square wave distortion, flubby. When I hit my boost pedal, I would then lose top end and quickly all sound would fizzle out, and fade back in when I turn off the boost. Boost and guitar work ok on other amps.

EMG battery? Something messed up on the front end of my Helios? Tubes?

_________________It started with a Crate combo and a grunge pedal

Last edited by misterspockyall on Thu, Jan 24, 2019 5:16pm, edited 3 times in total.

Yeah, check all the batteries involved. Have you tried just the guitar straight in? Lose all the effects and pedals and whatnot. Nothing else plugged in, just the guitar. If it still does that, first suspect would be tubes. I know when the battery in my delay pedal starts to go out, the sound begins to fade and fizzle out until the battery completely dies. So check your guitar battery too if you've got actives.

Tested new batteries, bottom line, any boosting of the front end causes the square wave distortion on the low end to the frequencies. I can even hear it when I roll the gain on the amp back. Sounds like a raspy fuzz pedal.

I pulled off the back cover to start rolling tubes, and I don't see any bias ports. The EL34 quad in the amp are labeled "23 4.8". The other known good quad I have are around 60 current, 8500 trans. I don't know how these numbers relate or how to proceed.

I own a multimeter, am fairly handy and can follow instructions if needed

Please remove any pedals and effects from the signal chain first. Just the guitar straight into the amp.

If the amp sounds fine like that, then it's the pedal.If the amp does not sound fine like that, then try replacing preamp tubes.If the amp does not sound fine like that, then try replacing the power tubes with a NEW set.

It's also rare, but maybe you're getting DC on your guitar from V1 grid/plate. But I would check the other things first.

Please remove any pedals and effects from the signal chain first. Just the guitar straight into the amp.

If the amp sounds fine like that, then it's the pedal.If the amp does not sound fine like that, then try replacing preamp tubes.If the amp does not sound fine like that, then try replacing the power tubes with a NEW set.

It's also rare, but maybe you're getting DC on your guitar from V1 grid/plate. But I would check the other things first.

I followed what you said the first time, leaving step 2. I’ll have some time to try this hopefully soon!

And replaced all 4 power tubes with an EL34 quad that Bogner sent to me. Same deal. If I hit the front with too much boost, it will literally fizzle out and not make a sound when I play. Even just with the emg's, bass heavy bar chords sound like a fuzz pedal.

If bias checks out, could be any number of things. Will need to go through the amp and make sure there are no bad solder joints and no bad resistors/caps. Start with the filter caps. If you don't know how to do this, you're better off taking it to a tech.

And replaced all 4 power tubes with an EL34 quad that Bogner sent to me. Same deal. If I hit the front with too much boost, it will literally fizzle out and not make a sound when I play. Even just with the emg's, bass heavy bar chords sound like a fuzz pedal.

Call and ask for Charlie at Bogner. Super cool guy. He helped me out with a 2006 Shiva in 2011. He well may tell you something we are not aware of.

Bought used :/ Looked perfect so I took a swing on it from eBay. I blew the mains fuse weeks ago when I had the loop jumpered to control volume to keep the channel volume high. But I replaced the fuse at Charley's suggestion and the amp performed flawlessly for weeks after with many many hours of use. I guess it could be related, but I only know enough to be dangerous with these things.

Amp modding/repair is on my bucket list, but I know I have a lot of homework to do before I go poking around with the chassis pulled. Hell, I don't even know how to bias this thing without the external points and pot. It's amazing how much I think I know until crap hits the fan in the real world

Bought used :/ Looked perfect so I took a swing on it from eBay. I blew the mains fuse weeks ago when I had the loop jumpered to control volume to keep the channel volume high. But I replaced the fuse at Charley's suggestion and the amp performed flawlessly for weeks after with many many hours of use. I guess it could be related, but I only know enough to be dangerous with these things.

Amp modding/repair is on my bucket list, but I know I have a lot of homework to do before I go poking around with the chassis pulled. Hell, I don't even know how to bias this thing without the external points and pot. It's amazing how much I think I know until crap hits the fan in the real world

In a hurry to rule out more issues, I swung by the local Sam Ash to get 5 JJ ECC83 tubes. I just opened them to swap them out in my amp, 3 of them were Fender labelled Sovteks!

I swear at the end of this I'm just going to switch to drums.

Scrounged together 5 good ECC83s to put in the Helios, fuzzy/fizzy low end and dies altogether when I boost it. I'm punting to the local tech. Thank you to everyone who contributed, this forum is priceless.

In a hurry to rule out more issues, I swung by the local Sam Ash to get 5 JJ ECC83 tubes. I just opened them to swap them out in my amp, 3 of them were Fender labelled Sovteks!

I swear at the end of this I'm just going to switch to drums.

Scrounged together 5 good ECC83s to put in the Helios, fuzzy/fizzy low end and dies altogether when I boost it. I'm punting to the local tech. Thank you to everyone who contributed, this forum is priceless.

Took it to a tech today who was kind enough to let me bring my guitar, boost, and head to play on their bench. I was getting the raspy fuzz sound when I'd boost it, but couldn't make it fizzle out(volume cut out) as I'd described before.

He threw it on the scope, Power and Preamp section checked out with no irregularities and he kept pointing to my guitar and pedal as the potential culprits. Guitar wiring checked out. On to the pedal. We could get it to get fuzzy boosting the amp, then he decided to mess with the pedal power supply... bingo. The same volume cutout and fuzz out I was experiencing at home.

In short, when I run EMG's or boost the front end, and roll the amp gain back in 80s Hot mode, it is a weird almost fuzz pedal like tone. But by their best tests without pulling the chassis, and now confirmed at home, the amp seems fine, my power supply connection for my pedal needs some attention.

I feel like an ass, but am glad they could sort it so quickly, and I'm grateful for everyone that chimed in.

I definitely isolated it, just thought I started hearing something in the tone that was exacerbated by the pedal. So I thought it was boost related as I only noticed it with the emg loaded guitar and or boost.

This is my first time really working with a Marshall voiced type circuit and I’m finally beginning to use less and less gain. Hearing some other folks clips, more and more I’m thinking I have no idea how to dial in a tone. Back to the basics

Yeah, when you trouble shoot stuff like this you NEED to eliminate all the pedals. Unplug them. Run straight into the amp. I thought you said you did that and still had problems? Either way, at least now you know

Yeah, when you trouble shoot stuff like this you NEED to eliminate all the pedals. Unplug them. Run straight into the amp. I thought you said you did that and still had problems? Either way, at least now you know

I plugged straight in with a few guitars/cables. My passive humbucker guitar sounded fine, my EMG loaded guitar (mild input boost) sounded like a fuzz box on the low frequencies when I rolled the amp gain back. It was worse with the pedal (major input boost). So I thought hitting the front of the amp was creating issues within the amp itself, as I didn't hear these tones when testing with two completely separate amps.

When I get home today I'll try to get a quick audio clip up to describe what I mean. It may just be a bi-product of the amp circuit. I may just be crazy lol

Ok, half of this stuff I post for posterity because I've learned so much from amp threads, so sorry I keep dragging this out.

The Helios is perfectly fine. The raspy fuzzy tones I'm describing are happening naturally when I have it in Hot 80s mode and I turn the gain knob way down on the amp. Just the way its wired i guess. And it was all exagerated by any type of front end boost. The boost pedal power supply was an unfortunate coincidence.

I got to happily play it for an hour or so here, it sounds as killer as ever, and I've learned to keep the gain past 12 o' clock in this mode. Thanks ya'll!

Who is online

Users browsing this forum: No registered users and 0 guests

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum